A man walks past a poster of Zanu-PF leader Emmerson Mnangagwa in Harare. Zimbabweans will go to the polls on Monday to elect new members of parliament and the president. Picture: Aaron Ufumeli/EPA-EFE

Harare, Zimbabwe - The United Nations human rights office says it is concerned at the growing number of reports of voter intimidation and threats of violence as Zimbabwe's historic election approaches next week.

Tuesday's statement notes reports, especially in rural areas, of people being forced to attend campaign rallies. It calls on authorities to ensure that all Zimbabweans can participate in the vote "free from fear."

At the same time, the statement welcomes the peaceful demonstrations and the presence of human rights groups ahead of the July 30 vote, the first since longtime leader Robert Mugabe stepped down in November under military pressure.

The race has narrowed between President Emmerson Mnangagwa, a former Mugabe deputy, and opposition challenger Nelson Chamisa. Mnangagwa has pledged a free and fair election, which is considered key to lifting international sanctions.